org.apache.solr.search.EarlyTerminatingSortingCollector Maven / Gradle / Ivy
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/*
* Licensed to the Apache Software Foundation (ASF) under one or more
* contributor license agreements. See the NOTICE file distributed with
* this work for additional information regarding copyright ownership.
* The ASF licenses this file to You under the Apache License, Version 2.0
* (the "License"); you may not use this file except in compliance with
* the License. You may obtain a copy of the License at
*
* http://www.apache.org/licenses/LICENSE-2.0
*
* Unless required by applicable law or agreed to in writing, software
* distributed under the License is distributed on an "AS IS" BASIS,
* WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
* See the License for the specific language governing permissions and
* limitations under the License.
*/
package org.apache.solr.search;
import java.io.IOException;
import java.util.Arrays;
import java.util.concurrent.atomic.AtomicBoolean;
import org.apache.lucene.index.IndexWriterConfig;
import org.apache.lucene.index.LeafReaderContext;
import org.apache.lucene.search.CollectionTerminatedException;
import org.apache.lucene.search.Collector;
import org.apache.lucene.search.FilterCollector;
import org.apache.lucene.search.FilterLeafCollector;
import org.apache.lucene.search.LeafCollector;
import org.apache.lucene.search.Sort;
import org.apache.lucene.search.SortField;
import org.apache.lucene.search.TopDocsCollector;
import org.apache.lucene.search.TopFieldCollector;
import org.apache.lucene.search.TotalHitCountCollector;
/**
* A {@link Collector} that early terminates collection of documents on a per-segment basis, if the
* segment was sorted according to the given {@link Sort}.
*
* NOTE: the {@code Collector} detects segments sorted according to a an {@link
* IndexWriterConfig#setIndexSort}. Also, it collects up to a specified {@code numDocsToCollect}
* from each segment, and therefore is mostly suitable for use in conjunction with collectors such
* as {@link TopDocsCollector}, and not e.g. {@link TotalHitCountCollector}.
*
*
NOTE: If you wrap a {@code TopDocsCollector} that sorts in the same order as the index
* order, the returned {@link TopDocsCollector#topDocs() TopDocs} will be correct. However the total
* of {@link TopDocsCollector#getTotalHits() hit count} will be vastly underestimated since not all
* matching documents will have been collected.
*
* @deprecated Use {@link TopFieldCollector} and set trackTotalHits to false.
* @lucene.experimental
*/
@Deprecated
final class EarlyTerminatingSortingCollector extends FilterCollector {
/**
* Returns whether collection can be early-terminated if it sorts with the provided {@link Sort}
* and if segments are merged with the provided {@link Sort}.
*/
public static boolean canEarlyTerminate(Sort searchSort, Sort mergePolicySort) {
final SortField[] fields1 = searchSort.getSort();
final SortField[] fields2 = mergePolicySort.getSort();
// early termination is possible if fields1 is a prefix of fields2
if (fields1.length > fields2.length) {
return false;
}
return Arrays.asList(fields1).equals(Arrays.asList(fields2).subList(0, fields1.length));
}
/** Sort used to sort the search results */
private final Sort sort;
/** Number of documents to collect in each segment */
private final int numDocsToCollect;
private final AtomicBoolean terminatedEarly = new AtomicBoolean(false);
/**
* Create a new {@link EarlyTerminatingSortingCollector} instance.
*
* @param in the collector to wrap
* @param sort the sort you are sorting the search results on
* @param numDocsToCollect the number of documents to collect on each segment. When wrapping a
* {@link TopDocsCollector}, this number should be the number of hits.
* @throws IllegalArgumentException if the sort order doesn't allow for early termination with the
* given merge policy.
*/
public EarlyTerminatingSortingCollector(Collector in, Sort sort, int numDocsToCollect) {
super(in);
if (numDocsToCollect <= 0) {
throw new IllegalArgumentException(
"numDocsToCollect must always be > 0, got " + numDocsToCollect);
}
this.sort = sort;
this.numDocsToCollect = numDocsToCollect;
}
@Override
public LeafCollector getLeafCollector(LeafReaderContext context) throws IOException {
Sort segmentSort = context.reader().getMetaData().getSort();
if (segmentSort != null && canEarlyTerminate(sort, segmentSort) == false) {
throw new IllegalStateException(
"Cannot early terminate with sort order "
+ sort
+ " if segments are sorted with "
+ segmentSort);
}
if (segmentSort != null) {
// segment is sorted, can early-terminate
return new FilterLeafCollector(super.getLeafCollector(context)) {
private int numCollected;
@Override
public void collect(int doc) throws IOException {
super.collect(doc);
if (++numCollected >= numDocsToCollect) {
terminatedEarly.set(true);
throw new CollectionTerminatedException();
}
}
};
} else {
return super.getLeafCollector(context);
}
}
public boolean terminatedEarly() {
return terminatedEarly.get();
}
}